During printing, after controlled deposition of a toner material to the print substrate, the toner is fixed to the print substrate. Various methods of fixing toner material are known. According to a conventional method, a heated fixing roll is rolled over the print substrate with the deposited toner thereon, with a predetermined pressure. In this manner, the toner adheres reliably to the substrate, and the toner particles are strongly attached to the print substrate or to the image support. In another method, the print substrate with the deposited toner is heated with energy radiation, and the toner is reliably attached to the print substrate under the effect of energy radiation only, without any mechanical action. When the print substrate and the toner are irradiated, e.g., with microwaves, with subsequent printing on the print substrate, the image on the first print side, which has been formed by the toner on the print substrate, may be damaged by mechanical action because the toner on the first print side is in the low-viscous condition. The printed image is, therefore, sensitive to a mechanical action during and after the fixing of the toner to the print substrate for some time, for example, because of contact with a transport belt, which feeds the printed matter through the printer.